Electric oil circuit breaker



P 1936- c. H. FLURSCHEIM ELECTRIC OIL CIRCUIT BREAKER Filed March 29, 1935 3 Sheets-Sheet l Inventor": Cedric H. Flurscheirn,

H is Attorn e Sept. 22, Q FLURSCHEIM 2,055,345

' ELECTRIC OIL CIRCUIT BREAKER Filed March 29, 1935 3 Sheets-Sheet 2 Inventor: Cedric H. Fmvscheim,

His Attor'h eg- Sept. 22, 1936- c. H. FLURSCHEIM ELECTRIC OIL CIRCUIT BREAKER Filed March 29, 1935 3 Sheets-Sheet 5 Inventor Cedric H. Flurscheim, llLJ Z 49 H s Attorneg- Patented Sept. 22, 1936 PATENT QFFHGE ELECTRIC OIL CIRCUIT BREAKER Cedric Harold Flurscheim, Fleet, England, assignor to General Electric Company, a corporation of New York Application March 29, 1935, Serial No. 14,750 In Great Britain April 13, 1934 5 Claims.

This invention relates to electric oil circuit breakers for high voltage systems and more particularly to circuit breakers of the kind in which the contacts are arranged in a substantially horizontal casing usually supported by a vertical pillar.

The invention has an important application inter alia to oil circuit breakers of the impulse type in which, during breaking, oil is forced between the contacts by a pump or other such device.

In the construction of circuit breakers of the kind above referred to it has previously been proposed to mount a horizontal casing consisting of an insulating bushing enclosing a plurality of sets of contacts on a centrally located support consisting of a hollow pillar of insulating material and to connect the moving contacts through an insulating rod with tripping and actuating gear at the base of the pillar.

According to the present invention a circuit breaker of the kind referred to includes a condenser bushing through which passes aconductor associated at one end or at both ends with an electrical contact or contacts the exterior of which condenser bushing is earthed and located within a main body portion mounted on a pillar or like supporting structure. Such an arrangement possesses advantages'in that it enables an earthed metal pillar to be employed in place of the insulating pillar of the prior arrangement and also permits the contact operating mechanism and, in the case of an impulse circuit breaker, the oil pumping device or devices to be mounted upon or within the main body portion. Either a single set of contacts may be employed or a plurality of sets providing a plurality of breaks in series. In all cases however it is desirable that the column of oil above the contacts which has to be displaced during breaking of the circuit shall be relatively small so that the flow of oil across the path of the moving contact is not unduly restricted.

Accordingly in cases in which a plurality of sets of contacts are employed the horizontal casing or insulating bushing is preferably only partly filled with oil so that upward displacement of the oil can take place, whereas in cases in which there is a single set of contacts at each end of the horizontal conductor the casing may be completely filled provided there is an oil vent at each end since the column of oil which has to be displaced by the explosion is shorter.

Whilst itis important that the column of oil displaced by the explosion or arc-extinguishing liquid blast shall be small it is also desirable to cover the bushing and the insulating tube with the oil so that the end of the bushing shall be washed by a flow of oil during each movement and hence one form of the invention comprises a single set of contacts at one end of the horizontal conductor and the casing is tilted so as to bring the contacts near to the surface of the oil.

According to a further feature of the invention, in order to reduce the overall horizontal length of the circuit breaker one or more of the moving contacts may be arranged on opening the circuit to telescope within the condenser bushing.

In order that the invention may be more clearly understood reference will be made to the examples shown in the accompanying drawings in which,

Fig. 1 is an elevational view of a horizontal type oi. circuit breaker having a plurality of breaks on each side of a central portion and in which the left-hand part as viewed is shown in outside elevation, part of the outer casing being broken away, and the right-hand side of the circuit breaker is shown generally in section.

Fig. 1A is a detail perspective view, partly in section, of contact and associated structure shown in Fig. l. a

Fig. 2 is an elevational, part sectional view of a horizontal type of circuit breaker providing for a single break only on the right-hand side of the circuit breaker, the circuit breaker being tilted vso that the point at which the break occurs is near to the surface of the oil.

Fig. 3 is a plan view generally in section of the arrangement shown in Fig. 2.

Fig. 4 is a side elevation of an arrangement for mounting a circuit breaker constructed according to the present invention so that it may be readily isolated and Fig. 5 is a side view of the arrangement shown in Fig.

In the construction shown in Fig.1 the two sides of the circuit breaker are similar and most of the parts are shown on one side only, however it will be understood that corresponding parts are at the other side of the circuit breaker.

In Fig- 1, the reference i indicates the condenser bushing surrounding a conductor 2, whilst 3 indicates the main body portion forming part of the breaker casing which houses the condenser bushing and which in turn is mounted on a metal pillar G. I

The outside of the condenser bushing is provided with a conductive layer, 5 which is earthed through the main body and pillar 4.

As'shown in the drawings the windings 5 or" a current transformer are located within the support housing around the condenser bushing.

Supported by the main body 3 and pr ojecting horizontally in each direction are insulating shel s forming arc shields l and 71'. At the ends of the arc shields there are provided metal end covers 3 and i3 respectively provided with terminals 9 and 9' and adjacent each end cover is a corona shield it or ill. Also mounted on the earthed housing 3 and extending laterally within the arc shields l and l are insulating housings M and l I wherein are located the moving contacts.

Referring to the right hand portion of Fig. l, and more particularly to Fig. 1A, it will be observed that the conductor 2 is connected by a flexible connection 112 with a moving contact is which is slidably mounted for longitudinal reciprocal movement on a pair of guide rods i l and i which coacts with a fixed contact E5. The contact is supported in an insulating bushing 85a in which is formed a cross jet passage lEb through which oil is forced across the path of the moving contact it into the space between the insulating housing ii and shield l. The fixed contact 135 is provided with a cylindrical extension is which in turn isconnected by a flexible connection ll with a second moving contact it which co-operates with a fixed contact is located in an insulated housing Eta in which is formed a similar cross jet passage, the contact l9 being connected through an extension 23 and conducting strip 2i with the end terminal cap 3.

The moving contacts are actuated by means of an arm 22 which is connected with the'moving contact is through a link 23, and the moving contact it is connected with the contact is by means of the rods it so as to be simultaneously actuated. The arm 22 is rigidly mounted on a pivot 25 and referring now to the left side of the figure it will be observed that the corresponding pivot 25' is rigid with an arm 26' outside of the insulating housing l l, and the arm 26' is connected through an insulating link 27' with a bell crank lever 28' which in turn is connected through rods passing down within the pillar with the main actuating mechanism.

The actuating mechanism is suitably connected with the plunger-s of oil pistons so that during circuit breaking oil is forced out laterally into the spaces within the insulating housing it so that pressure is set up causing the oil to flow through the cross jet passages. Shields 2s, 2d surround the outlets of the cross jet passages so as to act as targets for the oil jets and prevent the oil from impinging OITIIIIG outer insulat= ing arc shield 71, l'.

The desirable oil level is in this case indicated by the line X and it will be observedthat the arc shields which also act as oil containers are only partially filled so as to reduce the'column of liquid which has to be moved for extinguishing the are at each of the points of breaking. Such a circuit breaker may for instance be about 14 ft. in overall horizontal length and have four breaks in series with a final separation of about 5 inches for operation on 132,000 volts.

The arrangement shown in Figs. 2 and 3 differs from that shown in Fig. l in that the two sides are not the same owing to the fact that abreak is only provided on the right-hand side of the circuit breaker. Accordingly fresh reference numerals are used throughout. The central conaccepts the reference and is surrounded by a condenser bushing 32 having an outer conducting layer 33 and mounted in a main body portion 3 3. On the left side of the circuit breaker the conductor 3! and condenser bushing 32 extend within a rain shield 35 to a conductive end cap 36 which constitutes one terminal of the circuit breaker. On the right side of the circuit breaker is located a rain shield '37 and an insulating housing 38, both of which are mounted on the main body portion 36.

On the end of the conductor 3i within the housing 38 is mounted a support 39 for a pair of guide arms at along which slide a cross arm ll secured to the moving contact 42. The moving contact is provided with an extension 43 extending within the conductor 38 and sliding within a bushing M or other form of spring loaded contact through which electrical connection is made with the conductor 35. As will be readily appreciated by causing the extension 53 to slide within the conductor Si in a telescbpic manner an appreciable saving in horizontal length of the circuit breaker is efiected'. The moving contact #32 co-operates with a fixed contact 55 connected through a conducting strip 35 with an end terminal plate All and the conductor 65 is carried upon a support 68 in turn secured to the end of the insulating housing 38. Cross jet passages as provide for a flow of oil across the path of the moving contact whilst a corona shield 50 surrounds the moving contact when in its open position.

The actuation of the moving contact is affected through insulating rods El (see Hg. 3) which connect the cross arm ll with a pair of bell crank levers 52 mounted on a cross shaft 53 which in turn is connected through an arm 5 3 (see Fig. 2) and link 55 with an arm 56 mounted on a shaft 5? connected to the actuating mech-' arm 56 of the link and lever mechanism is shown. Oil is projected along the interior of the insulating housing 38 from an oil cylinder 58, the plunger of which is actuated through a connecting rod 59 and arm Gil mounted on a shaft 6i which in turn is again actuated by the actuating mechanism (not shown).

It will be readily appreciated from the drawing that by tilting the circuit breaker the point of break of the contacts is brought to'the surface 3;: of the oil. A suitable tilt for such an apparatus would be in the neighbourhood of 5 to the horizontal, whereby the insulating hous ing Sloan still be kept filled with oil, an ad vantage from a dielectric point of ew.

Figs. and 5 show an isolating as applied to a threc-phase system embodying a circuit breaker of the kind as shown in Figs. 2 and 3 in each of the phases;

In Fig. 5 the three individual circuit breakers are indicated by'the references A, B, 0 respectively. The centre body portion ill of each circuit breaker is carried on a horizontal supporting beam 62, the ends of which beam are in turn mounted on adjustable supports tit and 6S pro vided with a suitable mechanism, such, for instance, as a screw gear for raising and lowering the beam and hence the circuit breaker. At the lowerend of each circuit breaker, that is the left-hand end as viewed in Fig. 4-, there is a contact arm 6 5 which abuts against a fixed contact 65 carried on an insulating pillar lit and till right-hand end as viewed in Fig. 4 there is a contact arm 61 which abuts against a fixed contact 68 mounted on an insulating pillar 69 and also connected with line. In the position shown in Fig. 4 the circuit breaker is live. The contact 64 abuts against a contact 65 and similarly the contact 61 abuts against the contact 68. When, however, the circuit breaker is lowered after the circuit breaking operation thereof, the contacts 64 and 61 will be moved away from the fixed contacts 65 and 68 respectively so that the circuit breaker will be isolated.

It should be understood that my invention is not limited to specific details of construction and arrangement thereof herein illustrated, and that changes and modifications may occur to one skilled in the art without departing from th spirit of my invention.

I claim:-

1. An electric circuit breaker for high voltage power circuits comprising a casing, relatively movable contacts operable within said casing, a stationary circuit conductor extending within said casing for connection with said contacts, a bushing for insulating said conductor with respect to said casing, said bushing being recessed at one end for receiving one of said contacts, and operating means for moving the aforesaid contact into said bushing in the open circuit position.

2. An electric circuit breaker for high voltage power circuits comprising a generally cylindrical casing, relatively movable contacts operable within said casing, a circuit conductor extending longitudinally through said casing for connection with said contacts, the circuit through said breaker being generally along the longitudinal axis of said casing, a condenser-type bushing for insulating said conductor with respect to said casing, a current transformer encircling said bushing, and grounded metallic structure for housing said current transformer and for supporting said bushing and breaker casing.

3. An electric circuit breaker for high voltage power circuits comprising a casing including a generally cylindrical insulating member, relatively movable contacts operable at one end of said member, a stationary circuit conductor extending through the other end of said member and centrally thereof for connection with said contacts, a condenser-type bushing for said conductor, a grounded metallic housing for supporting said bushing and said insulating member, an outer conducting layer of said bushing being electrically connected to said housing, and a current transformer encircling said condenser bushing and mounted within said housing.

4. An electric circuit breaker for high voltage power circuits comprising a generally cylindrical casing, relatively movable contacts operable at one end of said casing, and an insulating arc extinguishing liquid in said casing, the are between said contacts being subjected to a blast of said liquid in the circuit opening operation, the longitudinal axis of said casing being inclined a comparatively small degree with respect to the horizontal position so that the surface level of said are extinguishing liquid is adjacent said contacts and the remainder of said casing is filled with said insulating liquid.

5. A circuit breaker for high voltage power circuits comprising a casing including a metallic housing portion and an insulating member supported by and mounted at opposite ends of said housing, relatively movable contacts operable within at least one of said insulating members, the longitudinal axis of said casing being generally in horizontal position and inclined a small degree towards the vertical so that the end of said one of said insulating members is slightly elevated, disconnecting contacts carried at the outer terminals of said insulating members, stationary disconnecting contacts arranged to coact therewith, and supporting structure connected to said housing for guiding said circuit breaker when the same is lowered and elevated with respect to said stationary disconnect contacts.

CEDRIC HAROLD FLURSCHEIM. 

